Laser-capture microdissection (LCM), invented by Dr. Lance Liotta at the NCI, has enabled researchers for the first time to be able to analyze purified populations of cells directly from pateint tissue samples. These popluations include, but are not limited to, cancer epithelial cells- cells which comprise only 1-2% of the total population of cells found in any non-hematopoetic dervied tumor (the rest being stromal cells, fibroblasts, infiltrating lymphocytes, etc.). In a close collaborative effort, I have become the lead investigator for the proteomic analysis of cancer cells from a variety of tissue types (prostate, breast, lung, esophogeal, lung, brain, ovary, colon) derived from laser-capture microdissected cells. Threse cells have been analysed via 2D-PAGE protein fingerprinting, High-throughput multiplexed RNase proection analysis of cell-cycle, apoptosis and cytokine screening, phophoprotein analysis, SELDI protein chip retentate mapping anlysis, mul;itplexed scanning immunoblot analysis. Additionally, serum and body fluid tumor marker identification is being performed via SELDI and 2D-PAGE analysis. We have found that we can successfully recover and analyze proteins from the LCM and have identified over one dozen proteins from prostate and esophogeal cancer that is differentially regulated (turned off or turned on). Currently, we are attempting to employ MS-MS de novo protein microsequencing on these proteins to identify (if known) or generate amino acid sequence for cloning of novel proteins. We have succesfully employed SELDI retentate mapping and phosphoprotein capture analysis on LCM derived cells and detected over 20 protein chnages that occur in porstate cancer cells when compared to there normal epithelial cell comparators.